Icebreaking tank ship

ABSTRACT

An icebreaking tank ship has an elongated hull with a bow and stern and a catamaran arranged above and connected to the hull, the elongated hull moving substantially under the icepack while the twin hulls of the catamaran are arranged to cut through the icepack, the bridge of the catamaran being spaced above the icepack.

United States Patent 119 3/1972 Haahemi 114/40 X Devine Aug. 28, 1973[54] ICEBREAKING TANK SHIP 3 1,817,742 8/1931 Escobedo 114/ 16 R3,494,318 2/1970 Kataumura.. 114/235 R [751 Devin" 3,537,413 11/1970'Farrell 114/43.s [7 3] Assignee: Esso Research and Engineering Company,Linden, NJ. Primary Examiner-Milton Buchler 22 Filed: N 19 1 1 41 1 9'"!?'7 1!1-- 135F129 1 0v 19 1 Attorney-Thomas B. McCulloch, Melvin F.Fincke [21] APPl- 2001307 and Timothy L. Burgess et a1.

[57] ABSTRACT [52] U.S. Cl. 114/40, 114/61, 114/16 [51] Int. Cl 1363b35/08 cebmkmg '1 flamed a 58 Field ofSearch 1 14 40-4'2,43.5,44, and anda mans 11 4 l 49 16 235 connected to the hull, the elongated hull movmgsubstantially under the icepack while the twin hulls of the 56]References Cited catamaran are arranged to cut through the icepack, the

UNITED STATES PATENTS bridge of the catamaran being spaced above theice- 1:. 3,429,287 2/1969 Uram 114/16 R P 1 Claim, 4 Drawing FiguresPATENTED MIC 28 I975 ff Tr INVENTOR. WALTER B- DEVINE,

THOMAS B. Mc CULLOCH ATTORNEY.

ICEBREAKING TANK SI-IIP BACKGROUND OF THE INVENTION above thecargo-carrying hull so that the icepack is below it. In its morespecific apsects, the invention involves a triple-hulled vessel having.an elongated cargocarrying hull and catamaran hulls connected to thelower hull and provided with means for cutting the icepack.

2. Description of the Prior Art It is known to provide submarine typevessels with a single hull projecting through the icepack. These vesselstend to follow cracks in the icepack and roll and thus have littlestability. It is also known to provide icebreaking vessels with detachedor connected prows having unbalanced weights which rotate to break theice with a hammer effect. Likewise, icebreakers with extensions on thebow which extend under the pack ice and break it by an upwardlyextending cam force. Knife blades on the prows of icebreakers are alsoknown. However, no one heretofore'has provided a combination asdescribed and claimed here of an elongated hull with upwardly extendingbow ice knife and catamaran hulls which cut through the pack ice. Thepresent invention is, therefore, new, useful and unobvious. Thefollowing listed U. S. Pat. Nos. were considered with respect to thisinvention: 499,296; 857,766;'993,440; 1,500,000; 3,045,628; 3,130,701;3,521,590; 3,572,273.

SUMMARY OF THE INVENTION The present invention may be briefly describedand summarized as involving an icebreaking vessel having an elongatedhull and a bow and stem for use in Arctic waters and having parallelwing walls which may be approximately midship of the elongated hullforming parallel hulls each having an ice bow and stem, the parallelhulls being connected to the elongated hull to extend above ice waterline while the elongated hull extends longitudinally substantially belowthe icepack. The outer of the wing walls extending outwardly from theelongated hull such that ice is causedto break downwardly and outwardlyof the elongated hull. Bridge means are spaced vertically from theelongated hull and interconnect the parallel hulls. The elongated hullis adapted to carry liquid or dry cargo such as oil or ore.

The elongated hull has upwardly extending curvilinear ice knifeextending from the bow toward the stern a sufficient distance to cutunder the icepack asthe vessel moves ahead or astern.

BRIEF DESCRIPTION OF THE DRAWING The present invention may be furtherillustrated by reference to the drawing in which FIG. I is a top partialsectional view of the ship of the present invention;

FIG. 2 is a side elevational partial sectional view of the presentinvention;

FIG. 3 isa front view of FIGS. 1 and 2; and

FIG. 4 illustrates the vessel in ice breaking position in Arctic waters.

DESCRIPTION OF THE'PREFERRED MODES AND EMBODIMENT WITH REFERENCE TO THEDRAWING Numeral l l designates the hull of an elongated vessel providedwith a bulbous bow l2 and having wing walls 13 which extend outwardlyfrom the walls 14 of the hull II. The wing walls I3 form hulls IS withwalls 16 which are joined to form ice prows I7 and stems 18. In short,spaced above the hull 11 are hulls 15 which are connected together bybridge means 19 to form a catamaran designated by the numeral 20.

The hull 11 is strengthened with transverse bulkheads 21 andlongitudinal bulkheads 22 which form tanks such as 23 which may be usedfor liquid or dry cargo such as oil or iron ore and the like. Arrangedon the bow of the vessel 11 and extending about 15 to 30 percent of thehull length are knives 24 which serve to cut the icepack as the hull 11moves ahead or astern in Arctic waters.

The hull 11 is provided with screw means 25 which may be two or more innumber and trim control means 26 as well as steering means 27. I

Stack means 28 extend upwardly through the hulls 13 to the atmospherefrom an engine room 29 which may contain one or more steam engines,diesel engines, or nuclear power means. These stacks may be used to ventgases, smoke, vapors, steam and the like.

In FIG. 1 the ice water line is shown as a shaded area 30 whichrepresents the cross-sectional area of hulls 15 with the ice beingbroken as will be more clearly understood from the description of FIG.3. The stem 31 of the vessel overhangs the trim control means 26, thesteering means 27 and the screw means 25. I

Referring to FIG. 2, it will be noted that the control cargo tanks 32 ofthe elongated hull 11 have access and ventilate to the atmosphere viathe ullage spaces 33 located in the wing walls 13. The ullage spaces 33extend upwardly in the hulls 15 and are closed by vented hatches 50. Incase of leaks which may occur in hull walls 14, the only cargo liquidlost would be that amount in space 33 which extends about the water lineas represented by D in FIG. 2. Pressure equalization would contain theremainder of the cargo liquid. The bridge means 19 providing officersand crew quarters and being spaced above the hull 15 a sufficientdistance so that the icepack moves beneath the bridge 19 while the hull11 is substantially below the icepack. Thisdistance may be in the rangeof about 30 to about 50 feet. In FIG. 2 the ice water line is indicatedby the numeral 42 and it is substantially cut by the ice bows 17 of thehulls 15, which causes the ice to move downward and outward from thehull 11. The ice knife 24, as stated, extends rearwardly on both sidesof the hull about 15 to 30 percent of the hull length and serves to cutloose the ice peaks formed beneath the ice layer while the ice bows 17are breaking up the ice layer at the surface. The ice peaks below theice layer are usually formed by ice particles and are usuallyunconsolidated masses of ice and vary in size, depth and spacing.

The present invention is quite advantageous and useful in that thevessel is provided with two verticalfins (hulls) transversely separatedwhich penetrate the ice surface, while most if not all of the elongatedhull is below the ice water line. The fins or hulls provide a minimumresistance to icebreaking, while providing the necessary stability andreserve buoyancy for a safe operation.

The vessel may be generally described as a semisubmersible catamaranicebreaking vessel consisting essentially of a main hull with two wingwalls on each side extending above the upper deck of the main hull. Thewing walls are joined at the top with the forward part supporting abridge structure which houses the ships personnel and controls for theship.

When the vessel is in open water, it is operated in the usual mannerwith freeboard. When the vessel enters the ice, water ballast is addedto the elongated hull and wing walls forming the twin hulls until themain hull is submerged and only the twin hulls are cutting through theice. The sum of the width of the twin hulls is about one quarter of thewidth of the main hull, thereby reducing resistance of the ice, makingforward progress of the vessel easy and fast. The twin hulls arepositioned and shaped in such a way that all the broken ice is forcedoutward and downward away from the main deck of the main hull. The shapeof the twin hulls at the ice water line is such that they taper to anarrow after end. The distance between the wing walls of the twin hullsat the ice water line is closer at the forward end and a greaterdistance apart at the after end. This distance may be from about 2percent to about 6 percent the length of the catamaran hulls. Thisspread permits the broken ice between the twin hulls to move freely aft.The outboard shape of the wing walls of the twin hulls at the ice waterline is curved from forward to aft, while the inboard'side is generallya straight line.

The two hulls are utilized in this invention to provide adequatetransverse stability to a semi-submersible hull while a single fincentrally located does not provide the same degree of stability as thepresent invention. In addition, the danger of a single fin is that itwill tend to follow a crack in the ice, and should the crack lead at anangle to the forward motion, a large vessel with little stability willroll rather than tum. The twin hulls fight this tendency in two ways:first, the amount of transverse stability is about 500 times greater,and secondly, it is unlikely that racks leading from two spaced aparthulls would lead in the exact same direction. In the event that the iceforce did start the vessel to roll, two additional forces come intoplay. First, the forward ice knife on the submerged hull begins cuttinginto the surface ice, tending to slow the vessel down. Second, as thevessel continues to roll, the main deck emerges and the wider portion ofthe wing wall submerges, both tending to stop the vessels roll. Theadditional stabilizing forces begin to act when the angle of roll isabout 12. The maiximum righting arm occurs around 25 which is greaterthan on conventional hulls.

The longitudinal stability of this invention is much less than that of anormal hull. The ice-breaking forces at the far portion of the wing wallwill tend to trim the vessel by the stern. By placing the ice how wellaft to the forward end of the vessel, say about 20 percent to about 40percent of the vessel length, the trimming movement is significantlyreduced. The ridge ice knife at the bow of the elongated hull is shapedto cut through ridges but not to give any net vertical force to the bowof the vessel, either up or down. The trim control at the stern providesthe necessary balancing force to keep the vessel on an even keel. Thevessel will cut through ridges rather quickly so that the very largeinertia of the vessel will prevent it from suddenly taking any largetrim angle.

Both rudders and trim control surfaces are placed in the propeller washso that trim and turning forces can be generated even with the vesselstanding still in ice or water. The trim control can also be useful inapproaching a loading facility in the ice. As ballast is removed tobring the main deck out of the water, the vessel must be trimmed by thestem to clear all the ice off the deck. As the bow emerges, the ice willbe pushed aside, forming an open water area for the vessels hull. Thesemisubmersible hull form of limited ice resistance can burn fossilfuels, whereas a submarine with no ice resistance requires the morecostly atomic or chemical power. The semi-submersible has the addedadvantage of primary depth control built into the hull shape, whereas asubmarine must rely on pressure sensors, mechanical control surfaces andvery fine weight control.

Machinery space in the semi-submersible of the present invention iscentrally located longitudinally under the wing walls to minimize thetrimming movement in case of flooding.

All of the above-mentioned features may apply to any vessel no matterwhat its function. The following will describe features that areparticularly useful for a vessel designed to carry petroleum products inbulk or liquid form.

A semi-submersible icebreaker is particularly suited for the carriage ofliquid products that are, broadly speaking, near the same density aswater. The wing walls must have sufficient stability and reservebuoyance to prevent sinking in the event of a rupture. The amount ofstability and reserve buoyance required is directly related to theamount of void spaces in the underwater portion of the vessel. Liquidcargoes tend to fully occupy the submerged hull. A change in buoyancy inthe event of rupture in a compartment already full of a liquid is verysmall. The size of the wing walls necessary to compensate for such achange is very small. This is not the case in carrying ore cargoes, forsuch vessels require a great quantity of void space to support highdensity ore.

The present invention, when designed for carrying oil with a densitylower than that of water, offers simplicity of design and safety ofoperation, particularly suited to the present configuration. When theunderwater hull other than machinery spaces is full of oil, its buoyancywill be positive; that is, the hull will tend to float. The wing wallsabove the water surface will then be used to carry water ballast inorder to sink the main hull to its operating depth and the ice waterline. The twin hull volume and configuration then serve a number ofunique functions in the tank vessel, as follows:

1. Provides transverse and longitudinal stability;

2. Provides the necessary above water ballast volume to submerge thehull to the appropriate ice water line;

3.Provides the ullage space for the cargo tanks to eliminate freesurface in the submerged hull;

4. Provides a location for the cargo tank vents;

5. Provides for air location to the fossil fuel machinery and exhaustspaces for gases of combustion;

6. Provides access between the navigation bridge and quarters to themachinery spaces including shaft tunnels;

7. Provides a collision rupturing wing ballast tank which will causewater to flow out of the hull,

thereby adding buoyancy instead of losing buoyancy.

A further advantage of carrying oil products in such a hull isdemonstrated in the event of grounding. The small cross-sectional areaof the ullage space above and below the ice water line will quicklyequalize the pressures between the outside waterhead and the internaloil head in the event of a rupture and very little flow in or out willoccur, thereby significantly reducing any pollution hazard.

The present invention provides a simple and unobvious tank ship which isreadily adapted for use in Arctic climes and in Arctic waters andprovides for transportation of either liquid or dry cargoes.

The ship of the present invention may have an elongated hull 1,000 feetin length with a beam of 200 feet. The catamaran hulls will be suitablysized for the length and beam of the elongated hull.

The nature and objects of the present invention having been completelydescribed and illustrated and the best modes and embodiments set forth,what I wish to claim as new and useful and to secure by Letters Patentl. The combination of an elongated hull having a bow and stern and acatamaran having a bridge connecting the catamaran, said catamaran beingarranged above and connected to said hull, said catamaran havingsufficient reserve buoyancy to prevent sinking in the event of a ruptureof the elongated hull;

said elongated hull floating below ice water line in a body of waterwhen ballasted or loaded andsaid catamaran being formed to cut throughan icepack in said body of water; said catamaran having outer wing wallswhich are an upward continuation and extension of outer walls of theelongated hull and the upward extension of the outer wing walls of thecatamaran are positioned and shaped so that they extend upwardly andoutwardly to force broken ice outward and downward away from theelongated hull.

1. The combination of an elongated hull having a bow and stern and acatamaran having a bridge connecting the catamaran, said catamaran beingarranged above and connected to said hull, said catamaran havingsufficient reserve buoyaNcy to prevent sinking in the event of a ruptureof the elongated hull; said elongated hull floating below ice water linein a body of water when ballasted or loaded and said catamaran beingformed to cut through an icepack in said body of water; said catamaranhaving outer wing walls which are an upward continuation and extensionof outer walls of the elongated hull and the upward extension of theouter wing walls of the catamaran are positioned and shaped so that theyextend upwardly and outwardly to force broken ice outward and downwardaway from the elongated hull.